A series of dielectric barrier discharge (DBD) experiments in helium at atmospheric pressure is carried out under a parallel electrode configuration. The discharge waveforms are observed in time-domain and analyzed in frequency-domain. Results show that under a certain condition the discharge can experience period-one, period-two and period-four discharges and finally enters into chaotic discharge as the amplitude of the driving voltage is increased. Our work verifies that the period-doubling route into chaos in DBD at atmospheric helium pressure can observed in experiment, beside in numerical simulations.